Placement of Reconfigurable Intelligent Surfaces in Urban Cell For Improved Coverage - A Practical Approach

Even though the 5G new radio (NR) system at mmWave frequencies provides large bandwidth and user data rates, it suffers severely from blockages and absorption losses, making its coverage limited to few meters. A wide range of new technologies and schemes are being investigated to overcome this coverage issue at high frequencies. Reconfigurable intelligent surfaces (RISs) is one among them. An RIS consists of a panel that reflects the incident signal towards the receiver, adding an extra signal path, thereby, aiding in extending the cell coverage. However, the placement and deployment of an RIS in the cellular system plays an important role in order to take the advantage of reflection. In this paper, we propose and analyse a practical method of RIS placement in an urban cellular network, that benefits all the users whose direct link from base station (BS) is blocked. We further propose a method in identifying the range of distance at which an RIS can be placed from a blocked region. We show that the RIS placement with the proposed method has around 8.2 dB gain in signal to interference and noise ratio (SINR), compared to randomly identified positioning methods, near to the network elements. We further show that the user coverage percentage improves significantly with the proposed method. We also discuss about a method through which blockage regions can be extracted from a real time system so that the suitable locations for RIS deployment can be chosen in 5G NR system.